JP2014127377A - Particle beam therapy system - Google Patents
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Abstract
Description
本発明は高精度の治療照射が可能な粒子線治療システムに関するものであり、特に、複雑な患部形状に一致した高精細な治療照射が可能なスキャニング法などの先端照射技術を用いた粒子線治療システムに係わる。 The present invention relates to a particle beam therapy system capable of high-accuracy treatment irradiation, and in particular, particle beam therapy using a tip irradiation technique such as a scanning method capable of high-definition treatment irradiation matching a complicated affected part shape. Related to the system.
近年の高齢化社会を反映し、がん治療法の一つとして、低侵襲で体に負担が少なく、治療後の生活の質が高く維持できる放射線治療が注目されている。その中でも、加速器で加速した陽子や炭素などの荷電粒子ビームを用いた粒子線治療システムが、患部への優れた線量集中性のため特に有望視されている。粒子線治療システムは、イオン源で発生したビームを光速近くまで加速するシンクロトロンなどの加速器と、加速器の出射ビームを輸送するビーム輸送系と、患部の位置や形状に合わせてビームを患者に照射する照射装置から構成される。 Reflecting the recent aging society, as one of the cancer treatment methods, radiotherapy that is minimally invasive, has less burden on the body, and can maintain a high quality of life after treatment is attracting attention. Among them, a particle beam therapy system using a charged particle beam such as proton or carbon accelerated by an accelerator is particularly promising because of excellent dose concentration on the affected area. The particle beam therapy system irradiates the patient with a beam according to the position and shape of the affected area, an accelerator such as a synchrotron that accelerates the beam generated by the ion source to near the speed of light, a beam transport system that transports the emitted beam of the accelerator It is comprised from the irradiation apparatus.
粒子線治療システムの照射装置で患部の形状に合わせてビームを照射する際、散乱体でビーム径を拡大したのちコリメータで周辺部を削ってビームを整形する散乱体法や、加速器からの細径ビームを電磁石で偏向し患部形状に合わせて走査するスキャニング法が用いられる。近年、複雑な患部形状に一致した高精細な治療照射が可能なスキャニング法が主流になりつつある。従来の散乱体法の場合と同様に、スキャニング法でも治療照射時間の短縮化の観点で、照射体積１Ｌ当たりの線量率２Ｇｙ／ｍｉｎが標準的な仕様値として要求される。 When irradiating a beam according to the shape of the affected area with the irradiation device of the particle beam therapy system, the beam diameter is enlarged with a scatterer and then the periphery is shaved with a collimator to shape the beam. A scanning method is used in which the beam is deflected by an electromagnet and scanned according to the shape of the affected area. In recent years, a scanning method capable of high-definition treatment irradiation that matches a complicated affected part shape is becoming mainstream. As in the case of the conventional scatterer method, the scanning method requires a dose rate of 2 Gy / min per 1 L of irradiation volume as a standard specification value from the viewpoint of shortening the treatment irradiation time.
スキャニング法では３次元的な患部形状を深さ方向の複数の層に分割し、各層を更に２次元的に分割して複数の照射スポットを設定する。深さ方向には照射ビームのエネルギーを変更して各層を選択的に照射し、各層内では電磁石で照射ビームを２次元的に走査して各照射スポットに所定の線量を与える。照射スポット間を移動中に照射ビームを連続的にＯＮし続ける方法をラスタースキャニングと称し、一方、移動中に照射ビームをＯＦＦする方法をスポットスキャニングと称する。何れのスキャニング法でも加速器にシンクロトロンを用いる場合には、荷電粒子ビームを患部の深さ方向の各層に対応したエネルギーまで加速したのちビーム輸送系へ出射し、ビーム輸送系を通して照射装置に輸送した荷電粒子ビームを該当する患部の層に選択的に照射する。 In the scanning method, a three-dimensional affected part shape is divided into a plurality of layers in the depth direction, and each layer is further divided two-dimensionally to set a plurality of irradiation spots. In the depth direction, the energy of the irradiation beam is changed to selectively irradiate each layer, and within each layer, the irradiation beam is two-dimensionally scanned with an electromagnet to give a predetermined dose to each irradiation spot. A method of continuously turning on the irradiation beam while moving between irradiation spots is referred to as raster scanning, and a method of turning off the irradiation beam during movement is referred to as spot scanning. In any scanning method, when using a synchrotron as an accelerator, the charged particle beam is accelerated to the energy corresponding to each layer in the depth direction of the affected area, then emitted to the beam transport system, and transported to the irradiation device through the beam transport system. A charged particle beam is selectively applied to the affected layer.
シンクロトロンの従来の運転方法では、前段加速器から入射した荷電粒子ビームを所定のエネルギーまで加速したのち、加速終了時のエネルギーで荷電粒子ビームを出射し、出射終了時の残留ビームを入射時のエネルギーまで減速して廃棄する。即ち、従来のシンクロトロンでは入射・加速・出射・減速の一連の運転周期を単純に繰り返し、１つの運転周期の出射期間中に単一エネルギーの荷電粒子ビームしか出射できなかった。そのため、スキャニング法で患部深さ方向の複数の層に対応して複数エネルギーの照射ビームが必要な場合には、シンクロトロンに周回ビームが十分残留していてもエネルギー変更の度に減速・入射・加速を再実施する必要があり、線量率の低下で治療照射時間が延長する問題があった。 In the conventional operation method of the synchrotron, the charged particle beam incident from the front stage accelerator is accelerated to a predetermined energy, then the charged particle beam is emitted with the energy at the end of acceleration, and the residual beam at the end of the extraction is used as the energy at the time of incidence. Decelerate until it is discarded. That is, in the conventional synchrotron, a series of operation cycles of incidence, acceleration, emission, and deceleration are simply repeated, and only a single-energy charged particle beam can be emitted during the emission period of one operation cycle. Therefore, when multiple scanning beams of multiple energy are required corresponding to multiple layers in the depth direction of the affected area by the scanning method, deceleration, incidence, Acceleration had to be re-executed, and there was a problem that the treatment irradiation time was prolonged due to a decrease in the dose rate.
その解決手段として特許文献１には、シンクロトロンの出射期間中に周回ビームを逐次加速あるいは減速して複数エネルギーの荷電粒子ビームを出射する運転方法が開示されている。特許文献１に記載のシンクロトロンの運転方法によれば、確かにエネルギー変更に必要な時間を短縮でき、線量率の向上により治療照射時間が短縮できる。しかし、標準的な仕様値として要求される照射体積１Ｌ当たりの線量率２Ｇｙ／ｍｉｎを達成するためには必ずしも十分ではない。 As a solution to this problem, Patent Document 1 discloses an operation method for emitting a charged particle beam having a plurality of energies by sequentially accelerating or decelerating a circular beam during the synchrotron emission period. According to the operation method of the synchrotron described in Patent Document 1, it is possible to surely reduce the time required for energy change, and shorten the treatment irradiation time by improving the dose rate. However, it is not always sufficient to achieve a dose rate of 2 Gy / min per 1 L of irradiation volume required as a standard specification value.
特許文献１の運転方法を具体化して炭素線治療用シンクロトロンで実験した結果が非特許文献１に開示されている。非特許文献１には、エネルギー変更の際の加速あるいは減速時にシンクロトロンからの不要な荷電粒子ビームの出射を抑制するために、加速あるいは減速に先だって四極電磁石で安定限界の大きさを拡大し、加速あるいは減速が終了した後に再び安定限界を縮小して元の大きさに戻す運転方法の記載がある。しかし、この方法ではインダクタンスが大きい四極電磁石の応答速度が遅くエネルギー変更に必要な時間が延長する問題がある。なお、上記問題に対して、インダクタンスが小さい高速応答の専用の四極電磁石をシンクロトロンに別途設けて対処する方法もあるが、シンクロトロンの大型化やコスト高を招き、特に小型・低コスト化が必須の陽子線治療用シンクロトロンでは現実的ではない。 Non-Patent Document 1 discloses the results of experiments using a synchrotron for carbon beam therapy embodying the operation method of Patent Document 1. In Non-Patent Document 1, in order to suppress the emission of an unnecessary charged particle beam from the synchrotron during acceleration or deceleration when changing energy, the size of the stability limit is expanded with a quadrupole electromagnet prior to acceleration or deceleration. There is a description of an operation method in which the stability limit is reduced again to return to the original size after the acceleration or deceleration ends. However, this method has a problem that the response speed of the quadrupole electromagnet having a large inductance is slow and the time required for energy change is extended. In addition, there is a method to deal with the above problem by providing a dedicated quadrupole electromagnet with low inductance and high-speed response separately to the synchrotron. However, this increases the size and cost of the synchrotron, and particularly reduces the size and cost. The essential proton therapy synchrotron is not realistic.
そこで、本発明の目的は、出射期間中に周回ビームを逐次加速あるいは減速してビームエネルギーを変更し、出射期間中に複数エネルギーの荷電粒子ビームを出射するシンクロトロンを用いた粒子線治療システムにおいて、エネルギー変更に必要な時間を短縮して線量率を向上し、スキャニング法での治療照射時間を短縮することである。また、その際に、シンクロトロンの大型化やコスト高を回避することである。 Accordingly, an object of the present invention is a particle beam therapy system using a synchrotron that emits a charged particle beam having a plurality of energies during an extraction period by sequentially accelerating or decelerating a circular beam during the extraction period to change the beam energy. This is to shorten the time required for energy change, improve the dose rate, and shorten the treatment irradiation time in the scanning method. At that time, it is to avoid the increase in size and cost of the synchrotron.
上記の目的を達成するために、本発明の粒子線治療システムは、前段加速器から入射した荷電粒子ビームを所定のエネルギーまで加速したのち、出射装置に印加した高周波電圧で安定限界を超えさせて荷電粒子ビームを出射するシンクロトロンと、前記シンクロトロンから出射された荷電粒子ビームを治療室まで導くビーム輸送系と、前記治療室で患者の患部形状に合わせて荷電粒子ビームを照射する照射装置とから構成され、前記シンクロトロンの出射期間中に荷電粒子ビームを逐次加速あるいは減速して複数エネルギーの荷電粒子ビームを出射し、加速あるいは減速中に前記シンクロトロンから出射される不要な荷電粒子ビームを前記ビーム輸送系で遮断する機能を有したものである。 In order to achieve the above object, the particle beam therapy system of the present invention accelerates the charged particle beam incident from the former accelerator to a predetermined energy, and then charges the charged particle beam by exceeding the stability limit with the high-frequency voltage applied to the extraction device. A synchrotron that emits a particle beam, a beam transport system that guides the charged particle beam emitted from the synchrotron to a treatment room, and an irradiation device that irradiates the charged particle beam according to the shape of the affected part of the patient in the treatment room The charged particle beam is sequentially accelerated or decelerated during the synchrotron emission period to emit a multi-energy charged particle beam, and the unnecessary charged particle beam emitted from the synchrotron during acceleration or deceleration is It has a function of blocking by the beam transport system.
望ましくは、本発明の粒子線治療システムは、荷電粒子ビームを逐次加速あるいは減速して複数エネルギーの荷電粒子ビームを出射する前記シンクロトロンの出射期間中に、前記シンクロトロンを構成する電磁石の制御で前記安定限界の大きさを実質的に一定に維持するとともに、加速あるいは減速時には出射装置に印加する高周波電圧をＯＦＦするものである。 Preferably, the particle beam therapy system according to the present invention is configured to control an electromagnet that constitutes the synchrotron during an emission period of the synchrotron that emits a charged particle beam of a plurality of energies by sequentially accelerating or decelerating the charged particle beam. The magnitude of the stability limit is maintained substantially constant, and the high-frequency voltage applied to the extraction device is turned off during acceleration or deceleration.
さらに望ましくは、本発明の粒子線治療システムは、前記シンクロトロンの出射期間中に荷電粒子ビームを逐次加速あるいは減速する際に、前記シンクロトロンの加速周波数の制御で前記安定限界の大きさを拡大して不要な荷電粒子ビームの出射を抑制するものである。 More preferably, the particle beam therapy system of the present invention expands the size of the stability limit by controlling the acceleration frequency of the synchrotron when sequentially accelerating or decelerating the charged particle beam during the synchrotron emission period. Thus, emission of unnecessary charged particle beams is suppressed.
また、上記の目的を達成するために、本発明の粒子線治療システムは、前段加速器から入射した荷電粒子ビームを所定のエネルギーまで加速したのち、出射装置に印加した高周波電圧で安定限界を超えさせて荷電粒子ビームを出射するシンクロトロンと、前記シンクロトロンから出射された荷電粒子ビームを治療室まで導くビーム輸送系と、前記治療室で患者の患部形状に合わせて荷電粒子ビームを照射する照射装置とから構成され、前記シンクロトロンの出射期間中に荷電粒子ビームを逐次加速あるいは減速して複数エネルギーの荷電粒子ビームを出射し、加速あるいは減速中に前記シンクロトロンの加速周波数の制御で前記安定限界の大きさを拡大して不要な荷電粒子ビームの出射を抑制する機能を有したものである。 In order to achieve the above object, the particle beam therapy system of the present invention accelerates the charged particle beam incident from the former accelerator to a predetermined energy, and then exceeds the stability limit with the high-frequency voltage applied to the extraction device. A synchrotron that emits a charged particle beam, a beam transport system that guides the charged particle beam emitted from the synchrotron to a treatment room, and an irradiation apparatus that irradiates the charged particle beam according to the shape of the affected part of the patient in the treatment room The charged particle beam is sequentially accelerated or decelerated during the synchrotron emission period to output a multi-energy charged particle beam, and the stability limit is controlled by controlling the acceleration frequency of the synchrotron during acceleration or deceleration. And the function of suppressing the emission of unnecessary charged particle beams.
本発明によれば、システムの大型化やコスト高を回避しつつ、出射期間中のエネルギー変更に必要な時間の短縮とビーム利用効率の改善で線量率を向上し、スキャニング法での治療照射時間を短縮できる。 According to the present invention, while avoiding an increase in size and cost of the system, the dose rate is improved by shortening the time required for energy change during the extraction period and improving the beam utilization efficiency, and the treatment irradiation time by the scanning method Can be shortened.
以下、図１〜図４を用いて、本発明の第１の実施形態による粒子線治療システムの構成及び動作について説明する。最初に図１を用いて、本実施形態による粒子線治療システムの全体構成について説明する。 Hereinafter, the configuration and operation of the particle beam therapy system according to the first embodiment of the present invention will be described with reference to FIGS. Initially, the whole structure of the particle beam therapy system by this embodiment is demonstrated using FIG.
粒子線治療システム１００は、ライナックのような前段加速器１１で予備加速した荷電粒子ビームを所定のエネルギーまで加速したのち出射するシンクロトロン２００と、シンクロトロンから出射された荷電粒子ビームを治療室４００まで導くビーム輸送系３００と、治療室４００で患者４１の患部形状に合わせて荷電粒子ビームを照射する照射装置５００と、制御装置６００とを備える。 The particle beam therapy system 100 includes a synchrotron 200 that emits after accelerating a charged particle beam preliminarily accelerated by a front accelerator 11 such as a linac to a predetermined energy, and a charged particle beam emitted from the synchrotron to a treatment room 400. A beam transport system 300 for guiding, an irradiation device 500 that irradiates a charged particle beam in accordance with the shape of the affected part of the patient 41 in the treatment room 400, and a control device 600 are provided.
制御装置６００は、前段加速器１１、シンクロトロン２００、ビーム輸送系３００、照射装置５００を構成する各機器及びその電源を制御し、シンクロトロンの運転シーケンスの各過程での制御と監視、及び照射装置でのビーム照射の制御と監視を司っている。なお、図１には本実施例に密接に関係する機器及びその電源との関係のみを、制御装置６００から伝送される指令信号（Ａ）〜（Ｄ）、（Ｆ）（Ｈ）を用いて明示している。 The control device 600 controls each device constituting the pre-stage accelerator 11, the synchrotron 200, the beam transport system 300, the irradiation device 500 and its power source, and controls and monitors each step of the operation sequence of the synchrotron, and the irradiation device He is responsible for the control and monitoring of beam irradiation. In FIG. 1, only the devices closely related to the present embodiment and the relationship with the power supply are shown using command signals (A) to (D), (F), and (H) transmitted from the control device 600. It is clearly stated.
シンクロトロン２００は、前段加速器１１で予備加速した荷電粒子ビームを入射する入射装置２４、荷電粒子ビームを偏向し一定の軌道上を周回させる偏向電磁石２１と励磁用電源２１Ａ、荷電粒子ビームが広がらないように水平／垂直方向に収束力を与える収束／発散型の四極電磁石２２と励磁用電源２２Ａ、高周波電圧で荷電粒子ビームを所定のエネルギーまで加速する加速空胴２５と励振用高周波電源２５Ａ、周回する荷電粒子ビームの振動振幅に対して安定限界を形成する六極電磁石２３と励磁用電源２３Ａ、電極間に印加した高周波電圧で荷電粒子ビームの振動振幅を増大し安定限界を超えさせて外部に取り出す出射装置２６と励振用高周波電源２６Ａ、荷電粒子ビームを出射するために偏向する出射偏向装置２７を備える。 The synchrotron 200 includes an incident device 24 that receives a charged particle beam preliminarily accelerated by the pre-accelerator 11, a deflecting electromagnet 21 that deflects the charged particle beam and circulates in a fixed orbit, an excitation power source 21A, and the charged particle beam does not spread. A converging / diverging type quadrupole electromagnet 22 and an excitation power source 22A that give a converging force in the horizontal / vertical directions, an acceleration cavity 25 that accelerates a charged particle beam to a predetermined energy with a high frequency voltage, and an excitation high frequency power source 25A. A hexapole electromagnet 23 that forms a stability limit for the vibration amplitude of the charged particle beam, the excitation power source 23A, and the high frequency voltage applied between the electrodes increases the vibration amplitude of the charged particle beam and exceeds the stability limit to the outside. An extraction device 26 to be taken out, a high-frequency power source 26A for excitation, and an output deflection device 27 that deflects to output a charged particle beam are provided.
次に図２を用いて、本実施形態による粒子線治療システムに用いるシンクロトロン２００の運転シーケンスの概要を説明する。図２において、横軸は時間ｔを示している。図２（Ａ）の縦軸は、制御装置６００から偏向電磁石２１の励磁電源２１Ａに伝送される指令信号に応じて、励磁電源２１Ａから偏向電磁石２１に供給される励磁電流を示している。図２（Ｂ）の縦軸は、制御装置６００から四極電磁石２２の励磁電源２２Ａに伝送される指令信号に応じて、励磁電源２２Ａから四極電磁石２２に供給される励磁電流を示している。図２（Ｃ）の縦軸は、制御装置６００から加速空胴２５の高周波電源２５Ａに伝送される指令信号に応じて、高周波電源２５Ａから加速空胴２５に供給される高周波電圧の周波数を示している。図２（Ｄ）の縦軸は、制御装置６００から六極電磁石２３の励磁電源２３Ａに伝送される指令信号に応じて、励磁電源２３Ａから六極電磁石２３に供給される励磁電流を示している。図２（Ｆ）の縦軸は、制御装置６００から出射装置２６の高周波電源２６Ａに伝送される指令信号に応じて、高周波電源２６Ａから出射装置２６に供給される高周波電圧の振幅値を示している。 Next, the outline of the operation sequence of the synchrotron 200 used in the particle beam therapy system according to the present embodiment will be described with reference to FIG. In FIG. 2, the horizontal axis indicates time t. The vertical axis in FIG. 2A indicates the excitation current supplied from the excitation power supply 21 </ b> A to the deflection electromagnet 21 in response to a command signal transmitted from the control device 600 to the excitation power supply 21 </ b> A of the deflection electromagnet 21. The vertical axis in FIG. 2B indicates the excitation current supplied from the excitation power supply 22A to the quadrupole electromagnet 22 in response to a command signal transmitted from the control device 600 to the excitation power supply 22A of the quadrupole electromagnet 22. The vertical axis in FIG. 2C indicates the frequency of the high-frequency voltage supplied from the high-frequency power supply 25A to the acceleration cavity 25 in response to a command signal transmitted from the control device 600 to the high-frequency power supply 25A of the acceleration cavity 25. ing. The vertical axis in FIG. 2D indicates the excitation current supplied from the excitation power supply 23A to the hexapole electromagnet 23 in response to a command signal transmitted from the control device 600 to the excitation power supply 23A of the hexapole electromagnet 23. . The vertical axis in FIG. 2F indicates the amplitude value of the high-frequency voltage supplied from the high-frequency power source 26A to the output device 26 in accordance with a command signal transmitted from the control device 600 to the high-frequency power source 26A of the output device 26. Yes.
シンクロトロン２００は、図２に示すように、入射・加速・出射・減速の一連の運転サイクルを繰り返す。入射期間には前段加速器１１で予備加速した荷電粒子ビームを入射・蓄積し、低エネルギーの荷電粒子ビームが一定の軌道上を安定に周回できるように制御装置６００が偏向電磁石２１と四極電磁石２２の励磁電流を設定する。加速期間には加速空胴２５に印加した高周波電圧で入射ビームをバンチ状に捕獲して加速し、加速とともに上昇する荷電粒子ビームの周回周波数に合わせて、制御装置６００が高周波電圧の周波数を増加させる。また、加速中の荷電粒子ビームが一定の軌道上を安定に周回できるように、制御装置６００は偏向電磁石２１と四極電磁石２２の励磁電流も荷電粒子ビームの加速とともに増加するよう制御する。出射準備期間には、制御装置６００は六極電磁石２３を励磁して、周回する荷電粒子ビームの振動振幅に対して安定限界を形成し、四極電磁石２２の励磁電流も加速終了時の値からビーム出射に最適な値に変化させる。これを出射条件の設定という。また、制御装置６００は出射装置２６に印加した高周波電圧で周回ビームの振動振幅を安定限界の付近まで増大させ、出射期間には周回ビームの振動振幅をさらに増大し安定限界を超えさせて出射する。本実施形態のシンクロトロンでは出射期間中に周回ビームを逐次加速して、一つの運転サイクルの出射期間中に複数のエネルギーレベルで荷電粒子ビームを出射する。なお、出射期間中の運転シーケンスは従来技術と比較しながら後で詳述する。減速準備期間には、制御装置６００は六極電磁石２３の励磁を停止して安定限界を消滅させ、四極電磁石２２の励磁電流も減速開始に最適な値に変化させる。これを出射条件の解除という。減速期間は加速期間とは逆の過程で、出射期間終了時の残留ビームを入射時エネルギーまで減速して廃棄する。 As shown in FIG. 2, the synchrotron 200 repeats a series of operation cycles of incident / acceleration / extraction / deceleration. During the incident period, the charged particle beam preliminarily accelerated by the pre-accelerator 11 is incident and accumulated, and the control device 600 allows the deflecting electromagnet 21 and the quadrupole electromagnet 22 to be able to stably circulate a low energy charged particle beam on a fixed orbit. Set the excitation current. During the acceleration period, the incident beam is captured in a bunch by the high frequency voltage applied to the acceleration cavity 25 and accelerated, and the control device 600 increases the frequency of the high frequency voltage in accordance with the circulating frequency of the charged particle beam that rises with acceleration. Let In addition, the control device 600 controls the exciting currents of the deflection electromagnet 21 and the quadrupole electromagnet 22 to increase with the acceleration of the charged particle beam so that the accelerated charged particle beam can stably circulate on a certain trajectory. During the extraction preparation period, the control device 600 excites the hexapole electromagnet 23 to form a stability limit with respect to the oscillation amplitude of the charged particle beam that circulates, and the excitation current of the quadrupole electromagnet 22 is also determined from the value at the end of acceleration. Change to the optimum value for emission. This is called emission condition setting. Further, the control device 600 increases the vibration amplitude of the orbiting beam to the vicinity of the stability limit with the high-frequency voltage applied to the extraction device 26, and further increases the vibration amplitude of the orbiting beam and exceeds the stability limit during the emission period. . In the synchrotron of this embodiment, the orbiting beam is sequentially accelerated during the emission period, and the charged particle beam is emitted at a plurality of energy levels during the emission period of one operation cycle. The operation sequence during the emission period will be described in detail later in comparison with the prior art. During the deceleration preparation period, the control device 600 stops the excitation of the hexapole electromagnet 23 to eliminate the stability limit, and changes the excitation current of the quadrupole electromagnet 22 to an optimum value for starting deceleration. This is called cancellation of the emission condition. The deceleration period is the reverse process of the acceleration period, and the residual beam at the end of the emission period is decelerated to the incident energy and discarded.
ここで、図８を用いて、本実施形態のシンクロトロンからの荷電粒子ビームの出射方法の原理について説明する。図８はシンクロトロンを周回する荷電粒子ビームの状態を、出射に関係する水平方向の位相空間内に示したものである。荷電粒子ビームを構成する各粒子は設計軌道を中心に振動しながら周回ビームＢＭとして周回する。横軸は設計軌道からのずれ（位置Ｐ）で、縦軸は設計軌道に対する傾き（角度θ）である。（ａ）は加速終了後で出射期間の開始前（出射準備期間中）、（ｂ）は出射期間中に安定限界の大きさをビーム出射に最適な状態に維持している場合の位相空間を示している。 Here, the principle of the method of emitting a charged particle beam from the synchrotron according to the present embodiment will be described with reference to FIG. FIG. 8 shows the state of the charged particle beam circulating around the synchrotron in a horizontal phase space related to emission. Each particle constituting the charged particle beam circulates as a circular beam BM while oscillating around the design trajectory. The horizontal axis is the deviation (position P) from the design trajectory, and the vertical axis is the inclination (angle θ) with respect to the design trajectory. (A) shows the phase space when the acceleration limit is maintained before the start of the emission period (during the emission preparation period), and (b) shows the phase space when the stability limit is maintained in an optimum state for beam emission during the emission period. Show.
出射準備期間に図１に示した六極電磁石２３を励磁することで、図８（ａ）に示すように、位相空間内に三角形状の安定限界（その内部を安定領域ＳＡと定義）が形成される。安定限界（安定領域ＳＡ）の大きさは、四極電磁石２２や六極電磁石２３の励磁電流で決まる。安定領域内の粒子はシンクロトロン内を安定に周回し続ける。このとき、図１に示した出射装置２６に高周波電圧を印加すると、周回ビームＢＭの振動振幅が増大して安定限界の付近まで広がる。そして、図８（ｂ）に示すように、出射期間中に安定限界を超えて安定領域ＳＡの外に出た粒子は、出射ブランチＥＢに沿って急激に振動振幅が増大し、最終的に出射偏向装置２７の開口部ＯＰに飛び込んで、出射ビームＢとしてシンクロトロンから取り出される。 By exciting the hexapole electromagnet 23 shown in FIG. 1 during the emission preparation period, a triangular stability limit (the inside is defined as a stable region SA) is formed in the phase space as shown in FIG. 8A. Is done. The magnitude of the stability limit (stable region SA) is determined by the excitation current of the quadrupole electromagnet 22 or the hexapole electromagnet 23. The particles in the stable region continue to circulate stably in the synchrotron. At this time, when a high frequency voltage is applied to the emission device 26 shown in FIG. 1, the vibration amplitude of the circular beam BM increases and spreads to the vicinity of the stability limit. Then, as shown in FIG. 8 (b), the particles that have exceeded the stability limit during the emission period and have moved out of the stable region SA suddenly increase in vibration amplitude along the emission branch EB, and finally exit. It jumps into the opening OP of the deflecting device 27 and is taken out from the synchrotron as an outgoing beam B.
再び図１において、ビーム輸送系３００について説明する。ビーム輸送系３００は、シンクロトロンの出射ビームを磁場で偏向して所定の設計軌道に沿って治療室４００内の照射装置５００に導く偏向電磁石３１、輸送中に荷電粒子ビームが広がらないように水平／垂直方向に収束力を与える収束／発散型の四極電磁石３２、照射装置５００への荷電粒子ビームの供給をＯＮ／ＯＦＦするビーム遮断用電磁石３３と励磁用電源３３Ａ、ビーム遮断用電磁石３３で除去したビームを廃棄するビームダンプ３４を備える。 Referring again to FIG. 1, the beam transport system 300 will be described. The beam transport system 300 includes a deflecting electromagnet 31 that deflects the emitted beam of the synchrotron with a magnetic field and guides it to the irradiation device 500 in the treatment room 400 along a predetermined design trajectory, and is horizontal so that the charged particle beam does not spread during transport. / Converging / diverging type quadrupole electromagnet 32 that gives a converging force in the vertical direction, beam blocking electromagnet 33 that turns on / off the supply of charged particle beam to the irradiation device 500, excitation power source 33A, and beam blocking electromagnet 33 A beam dump 34 for discarding the processed beam is provided.
なお、ビーム遮断用電磁石３３としては、励磁した際の２極磁場で不要ビームを偏向してビームダンプ３４で廃棄する方法と、励磁した際の２極磁場で偏向したビームのみ照射装置５００に供給する方法がある。前者はビーム輸送系の調整が簡単であり、後者は機器異常時に照射装置への荷電粒子ビームの供給が確実に遮断されるので安全性が高い。どちらの方法も可能であるが、本実施形態では前者の場合について記述する。 As the beam blocking electromagnet 33, a method of deflecting an unnecessary beam with a dipole magnetic field when excited and discarding it with a beam dump 34, and only a beam deflected with a dipole magnetic field when excited is supplied to the irradiation device 500. There is a way to do it. The former is easy to adjust the beam transport system, and the latter is highly safe because the supply of the charged particle beam to the irradiation device is reliably cut off when the equipment is abnormal. Either method is possible, but in the present embodiment, the former case will be described.
次に、図３を用いて本実施形態による粒子線治療システムに用いる照射装置５００の構成と動作原理について説明する。図３（ａ）は正面図であり、図３（ｂ）は患部に照射される荷電粒子ビームをその上流側から見た平面図である。照射装置５００はラスタースキャニング法を用いており、ビーム輸送系３００で導かれた荷電粒子ビームを水平及び垂直方向に偏向し患部４２の断面形状に合わせて２次元的に走査する走査電磁石５１、荷電粒子ビームの位置、サイズ（形状）、線量を監視する各種ビームモニタ５２を備える。 Next, the configuration and operation principle of the irradiation apparatus 500 used in the particle beam therapy system according to the present embodiment will be described with reference to FIG. FIG. 3A is a front view, and FIG. 3B is a plan view of the charged particle beam irradiated to the affected part as viewed from the upstream side. The irradiation apparatus 500 uses a raster scanning method, and the charged particle beam guided by the beam transport system 300 is deflected in the horizontal and vertical directions to scan two-dimensionally according to the cross-sectional shape of the affected part 42, charged Various beam monitors 52 for monitoring the position, size (shape), and dose of the particle beam are provided.
図３（ａ）に示すように、治療計画では患者４１の患部４２に対して、その３次元的な患部形状を深さ方向の複数の層に分割する。そして、シンクロトロンの出射ビームのエネルギー変更で照射ビームのエネルギーを変更して各層を選択的に照射する。図３（ｂ）に示すように、各層内では走査電磁石５１で照射ビームを２次元的に連続走査し各照射領域に所定の一様線量分布を与える。 As shown in FIG. 3A, in the treatment plan, the three-dimensional affected part shape of the affected part 42 of the patient 41 is divided into a plurality of layers in the depth direction. Each layer is selectively irradiated by changing the energy of the irradiation beam by changing the energy of the outgoing beam of the synchrotron. As shown in FIG. 3B, in each layer, a scanning electromagnet 51 continuously scans the irradiation beam two-dimensionally to give a predetermined uniform dose distribution to each irradiation region.
ここで、本実施形態の粒子線治療システムに関して、シンクロトロン出射期間中の詳細な運転シーケンス及び運転パラメータの時間変化について説明する。本実施形態の説明図を図４に、従来技術の説明図を図７に示し、本実施形態の運転シーケンスを従来技術の場合と比較しながら相違点を以下に述べる。 Here, regarding the particle beam therapy system of the present embodiment, a detailed operation sequence and a temporal change of operation parameters during the synchrotron emission period will be described. FIG. 4 is an explanatory diagram of the present embodiment, and FIG. 7 is an explanatory diagram of the prior art. Differences will be described below while comparing the operation sequence of the present embodiment with that of the prior art.
図４と図７は、図２で説明した出射期間を詳細化したもので、横軸は同様に時間ｔを示している。図４と図７において、（Ａ）〜（Ｃ）（Ｆ）の縦軸も、既に説明済みの図２（Ａ）〜（Ｃ）（Ｆ）の縦軸と同様である。一方、図４（Ｅ）と図７（Ｅ）の縦軸は、安定限界内側の安定領域の面積（図８の三角形ＳＡの面積）を示している。図４（Ｇ）と図７（Ｇ）の縦軸は、シンクロトロン２００からビーム輸送系３００に出射される出射ビーム電流を示している。図４（Ｈ）の縦軸は、制御装置６００からビーム遮断用電磁石３３の励磁電源３３Ａに伝送される指令信号に応じて、励磁電源３３Ａからビーム遮断用電磁石３３に供給される励磁電流のＯＮ／ＯＦＦ状態を示している。図４（Ｉ）と図７（Ｉ）の縦軸は、照射装置５００から患者４１の患部４２に照射される照射ビーム電流を示している。 4 and 7 show details of the emission period described in FIG. 2, and the horizontal axis similarly shows the time t. 4 and 7, the vertical axes of (A) to (C) and (F) are the same as the vertical axes of FIGS. 2 (A) to (C) and (F) already described. On the other hand, the vertical axis in FIGS. 4E and 7E indicates the area of the stable region inside the stability limit (the area of the triangle SA in FIG. 8). The vertical axis of FIG. 4G and FIG. 7G indicates the outgoing beam current emitted from the synchrotron 200 to the beam transport system 300. In FIG. 4H, the vertical axis indicates ON of the excitation current supplied from the excitation power source 33A to the beam cutoff electromagnet 33 in response to a command signal transmitted from the control device 600 to the excitation power source 33A of the beam cutoff electromagnet 33. / OFF state. The vertical axis in FIG. 4 (I) and FIG. 7 (I) indicates the irradiation beam current irradiated from the irradiation device 500 to the affected part 42 of the patient 41.
図４と図７では、出射期間中の出射区間１、出射区間２、出射区間３で、それぞれ、エネルギーＥ１、エネルギーＥ２、エネルギーＥ３と、段階的に逐次高いエネルギーの荷電粒子ビームをシンクロトロンから出射して患部に照射する場合を示している。出射期間中のエネルギー変更区間では、シンクロトロンを周回する荷電粒子ビームを追加速して、それぞれエネルギーをＥ１からＥ２、Ｅ２からＥ３へと高めている。エネルギー変更区間で周回ビームを追加速する際には、図２で説明した加速期間と同様に、制御装置６００は、偏向電磁石と四極電磁石の励磁電流を増加し、加速空胴に印加する高周波電圧の周波数（加速周波数）を高めるように制御する。治療で必要なエネルギー（Ｅ１、Ｅ２、Ｅ３）以外の荷電粒子ビームが患部に照射されないように、エネルギー変更区間では、シンクロトロンからの出射ビーム電流を極力低減して照射ビーム電流を抑制することが必須である。 In FIGS. 4 and 7, the charged particle beam of energy E1, energy E2, and energy E3, and gradually higher energy from the synchrotron in each of the emission period 1, the emission period 2, and the emission period 3 in the emission period. The case where it radiates | emits and irradiates an affected part is shown. In the energy change section during the emission period, the charged particle beam that goes around the synchrotron is added at an additional speed to increase the energy from E1 to E2 and from E2 to E3, respectively. When the additional speed of the orbiting beam is increased in the energy change section, the control device 600 increases the excitation current of the deflection electromagnet and the quadrupole electromagnet and applies the high frequency voltage applied to the acceleration cavity, as in the acceleration period described in FIG. Is controlled to increase the frequency (acceleration frequency). In the energy change section, the beam current emitted from the synchrotron can be reduced as much as possible to suppress the irradiation beam current so that the affected part is not irradiated with a charged particle beam other than the energy (E1, E2, E3) required for treatment. It is essential.
従来技術では、図７（Ｂ）の如く、追加速に先だって四極電磁石の励磁電流を調整して、図７（Ｅ）の如く、安定限界の大きさ（安定領域の面積）を拡大し、出射に最適な運転条件から外している。これを出射条件の解除という。また、追加速の終了後に再び四極電磁石の励磁電流を調整して、安定限界の大きさ（安定領域の面積）を縮小して、出射に最適な運転条件に戻している。これを出射条件の再設定という。ここで、図８のビーム出射に関する位相空間で説明すると、出射条件の解除の際には図８（ｂ）から図８（ｃ）へ、出射条件の再設定の際には図８（ｃ）から図８（ｂ）へと状態が遷移することになる。ここで、図８（ｂ）は出射期間中に安定限界の大きさをビーム出射に最適な状態に維持している場合、図８（ｃ）は出射期間中のエネルギー変更時に安定限界の大きさを拡大してビーム出射を抑制した場合の位相空間をそれぞれ示している。 In the prior art, as shown in FIG. 7 (B), the excitation current of the quadrupole electromagnet is adjusted prior to the additional speed, and the size of the stability limit (area of the stable region) is expanded as shown in FIG. 7 (E). The operating conditions are not optimal. This is called cancellation of the emission condition. Further, after the additional speed is completed, the excitation current of the quadrupole electromagnet is adjusted again to reduce the size of the stability limit (the area of the stable region) and return to the optimum operating condition for emission. This is called resetting the emission conditions. Here, the phase space relating to the beam emission in FIG. 8 will be described. When the emission condition is canceled, FIG. 8B to FIG. 8C, and when the emission condition is reset, FIG. 8C. The state transitions from FIG. 8B to FIG. Here, FIG. 8B shows a case where the magnitude of the stability limit is maintained in an optimum state for beam emission during the emission period, and FIG. 8C shows the magnitude of the stability limit when energy is changed during the emission period. The phase spaces when the beam emission is suppressed by enlarging the angle are respectively shown.
このように従来技術では、四極電磁石の励磁電流の調整で安定限界の大きさ（安定領域の面積）を拡大し、エネルギー変更区間においてシンクロトロンからのビーム出射を抑制できる。しかし、この方法ではインダクタンスが大きい四極電磁石の応答速度が遅くエネルギー変更に必要な時間が延長する問題がある。即ち、図７の運転シーケンスで、出射条件の解除と再設定に必要な時間が長くなり、エネルギー変更区間が延長する問題がある。 As described above, in the conventional technique, the magnitude of the stability limit (area of the stable region) can be expanded by adjusting the excitation current of the quadrupole electromagnet, and the beam emission from the synchrotron can be suppressed in the energy change interval. However, this method has a problem that the response speed of the quadrupole electromagnet having a large inductance is slow and the time required for energy change is extended. That is, in the operation sequence of FIG. 7, there is a problem that the time required for canceling and resetting the emission condition becomes long and the energy change section is extended.
それに対して本実施形態では、図４（Ｂ）と図４（Ｅ）実線の如く、出射期間中に安定限界の大きさ（安定領域の面積）を一定に維持するように制御装置６００が四極電磁石の励磁電流を制御し、出射条件の解除や再設定の調整を実施していない。（位相空間において、図８（ｂ）の状態を維持） また、エネルギー変更区間では、図４（Ｆ）の如く、制御装置６００が出射装置２６に印加する高周波電圧（出射高周波）をＯＦＦ（停止）するように制御し、一定に維持した安定限界を超えて出射される粒子数を極力低減している。理想的には、これで十分にエネルギー変更区間の出射ビーム電流を抑制できる。しかし実際には、電磁石の励磁電流リップルや周回ビームの不安定性および残留ガスとの散乱等の様々な擾乱により、図４（Ｇ）実線の如く、エネルギー変更区間においてスキャニング照射法では許容できないレベルの出射ビーム電流が生じることが、発明者のシンクロトロンの運転経験で見出された。勿論、エネルギー変更区間において、制御装置６００がシンクロトロンを構成する四極電磁石や六極電磁石の励磁電流を調整して安定限界の大きさ（安定領域の面積）を多少拡大する方法もあるが、その分だけエネルギー変更時間が延長する。そこで、本実施形態では図４（Ｈ）の如く、ビーム輸送系に設置したビーム遮断用電磁石を励磁して、エネルギー変更区間においてシンクロトロンから出射される不要な荷電粒子ビームを偏向して廃棄し、図４（Ｉ）に示す理想的な照射ビーム電流を実現している。 On the other hand, in the present embodiment, as shown by the solid lines in FIGS. 4B and 4E, the control device 600 has four poles so as to maintain the magnitude of the stability limit (area of the stable region) constant during the emission period. The excitation current of the electromagnet is controlled, and the exit condition is not canceled or reset. (In the phase space, the state shown in FIG. 8B is maintained.) Also, in the energy change section, as shown in FIG. 4F, the high frequency voltage (outgoing high frequency) applied to the emission device 26 by the control device 600 is turned off (stopped). ), And the number of particles emitted beyond the stability limit maintained constant is reduced as much as possible. Ideally, this can sufficiently suppress the outgoing beam current in the energy change section. However, in reality, due to various disturbances such as the excitation current ripple of the electromagnet, the instability of the circulating beam, and the scattering with the residual gas, the scanning irradiation method has an unacceptable level in the energy change section as shown by the solid line in FIG. It has been found in the inventor's experience with operating the synchrotron that an exit beam current is produced. Of course, in the energy change section, there is a method in which the control device 600 adjusts the excitation current of the quadrupole electromagnet and the hexapole electromagnet constituting the synchrotron to slightly increase the size of the stability limit (the area of the stable region). Increases energy change time by minutes. Therefore, in this embodiment, as shown in FIG. 4 (H), the beam blocking electromagnet installed in the beam transport system is excited to deflect and discard unnecessary charged particle beams emitted from the synchrotron in the energy change section. The ideal irradiation beam current shown in FIG. 4I is realized.
本実施形態では、シンクロトロンの出射期間中に周回ビームを段階的に逐次加速して、出射期間中に複数エネルギーの荷電粒子ビームを出射する場合を説明した。しかし、シンクロトロンの運転方法として、前段加速器から入射した荷電粒子ビームを加速期間に最大エネルギーまで加速し、出射期間中に段階的に逐次減速しながら複数エネルギーの荷電粒子ビームを出射する場合であってもよい。また、シンクロトロンの出射期間中に任意の加速・減速を組み合わせて複数エネルギーの荷電粒子ビームを出射する場合であってもよい。 In the present embodiment, the case has been described in which the circular beam is sequentially accelerated stepwise during the synchrotron emission period, and a charged particle beam having a plurality of energies is emitted during the emission period. However, the synchrotron is operated by accelerating the charged particle beam incident from the previous accelerator to the maximum energy during the acceleration period and emitting multiple energy charged particle beams while gradually decelerating during the extraction period. May be. Further, it may be a case where a charged particle beam having a plurality of energies is emitted by combining arbitrary acceleration and deceleration during the emission period of the synchrotron.
また、本実施形態の照射装置では、患部の照射スポット間を移動中に照射ビームを連続的にＯＮし続けるラスタースキャニング法を採用したが、照射スポット間を移動中に照射ビームをＯＦＦするスポットスキャニング法を採用した場合であっても同様の効果を奏する。 In the irradiation apparatus of the present embodiment, the raster scanning method is used in which the irradiation beam is continuously turned on while moving between the irradiation spots of the affected part. However, spot scanning that turns off the irradiation beam while moving between the irradiation spots is used. Even if the method is adopted, the same effect is obtained.
本実施形態によれば、出射期間中に周回ビームを逐次加速あるいは減速してビームエネルギーを変更する際に、制御装置６００がシンクロトロンから出射される不要な荷電粒子ビームを抑制するために、シンクロトロンの電磁石の制御で安定限界の大きさを拡大したり縮小したりする必要がなくなる。これにより、エネルギー変更に必要な時間を短縮して線量率を向上し、スキャニング法での治療照射時間を短縮できる。 According to this embodiment, when the beam energy is changed by sequentially accelerating or decelerating the orbiting beam during the emission period, the control device 600 suppresses unnecessary charged particle beams emitted from the synchrotron. Controlling the TRON electromagnet eliminates the need to increase or decrease the stability limit. Thereby, the time required for energy change can be shortened to improve the dose rate, and the treatment irradiation time in the scanning method can be shortened.
また、本実施形態によれば、粒子線治療システムの制御装置が、シンクロトロンの出射期間中に安定限界の大きさを実質的に一定に維持し、さらにエネルギー変更の際の加速あるいは減速時に出射装置に印加する高周波電圧をＯＦＦ（停止）することで、シンクロトロンから出射される不要な荷電粒子ビームを低減できる。これにより、ビーム輸送系で廃棄すべき荷電粒子ビームを低減でき、荷電粒子ビームの利用効率を改善して線量率を向上し、スキャニング法での治療照射時間を短縮できる。 In addition, according to the present embodiment, the control device of the particle beam therapy system keeps the magnitude of the stability limit substantially constant during the synchrotron emission period, and further emits at the time of acceleration or deceleration when changing energy. By turning off (stopping) the high frequency voltage applied to the apparatus, unnecessary charged particle beams emitted from the synchrotron can be reduced. Thereby, the charged particle beam to be discarded in the beam transport system can be reduced, the utilization efficiency of the charged particle beam can be improved, the dose rate can be improved, and the treatment irradiation time by the scanning method can be shortened.
さらに、本実施形態によれば、インダクタンスが小さい高速動作の専用電磁石をシンクロトロンに別途設けて対処する必要も無く、システムの大型化やコスト高を回避できる。 Furthermore, according to the present embodiment, there is no need to separately provide a dedicated electromagnet with a small inductance and a high-speed operation in the synchrotron, and an increase in system size and cost can be avoided.
本発明の第２の実施形態による粒子線治療システムの構成及び動作について説明する。本実施形態による粒子線治療システムの全体構成は第１の実施形態の図１と同様であり、シンクロトロンの運転シーケンスも出射期間を除いて第１の実施形態の図２と同様である。また、照射装置の構成や動作原理も第１の実施形態の図３と同様である。そこで、第１の実施形態と相違点があるシンクロトロンの出射期間中の運転シーケンスに関して以下説明する。 The configuration and operation of the particle beam therapy system according to the second embodiment of the present invention will be described. The overall configuration of the particle beam therapy system according to this embodiment is the same as that of FIG. 1 of the first embodiment, and the operation sequence of the synchrotron is the same as that of FIG. 2 of the first embodiment except for the emission period. Further, the configuration and operation principle of the irradiation apparatus are the same as those in FIG. 3 of the first embodiment. The operation sequence during the synchrotron emission period, which is different from the first embodiment, will be described below.
シンクロトロン出射期間中の詳細な運転シーケンス及び運転パラメータの時間変化を示す図４において、破線は第２の実施形態に対応し、第１の実施形態からの相違点を示している。図４（Ｃ）（Ｅ）破線の如く、本実施形態では、制御装置６００がエネルギー変更区間で加速空胴に印加する高周波電圧の周波数（加速周波数）を制御し、安定限界の大きさ（安定領域の面積）を拡大している。図８のビーム出射に関する位相空間で説明すると、エネルギー変更区間の開始時に図８（ｂ）から図８（ｃ）へ、エネルギー変更区間の終了時に図８（ｃ）から図８（ｂ）へと状態が遷移することになる。これにより、図４（Ｇ）破線の如く、エネルギー変更区間においてシンクロトロンから出射される出射ビーム電流が抑制される。 In FIG. 4 showing the detailed operation sequence and the time change of the operation parameters during the synchrotron emission period, the broken line corresponds to the second embodiment and shows a difference from the first embodiment. As shown by broken lines in FIGS. 4C and 4E, in the present embodiment, the control device 600 controls the frequency (acceleration frequency) of the high-frequency voltage applied to the accelerating cavity in the energy change section, and the stability limit size (stable The area of the area is expanded. Referring to the phase space related to beam emission in FIG. 8, from the state shown in FIG. 8 (b) to FIG. 8 (c) at the start of the energy change interval, and from the state shown in FIG. 8 (c) to FIG. The state will transition. Thereby, as shown by the broken line in FIG. 4G, the outgoing beam current emitted from the synchrotron in the energy change section is suppressed.
偏向電磁石や四極電磁石の励磁電流が一定の状態で加速周波数のみを制御すると、周回ビームのエネルギーが変化するとともに、周回軌道の位置も変化する。前者は周回ビームに対する水平／垂直方向の収束力に影響を与え、四極電磁石の励磁電流の調整と同様な効果がある。また、後者は周回軌道が六極電磁石の中心位置から変位することで周回ビームに対する水平／垂直方向の収束力に影響を与え、やはり四極電磁石の励磁電流の調整と同様な効果がある。両者の効果を上手く組み合わせ安定限界の大きさ（安定領域の面積）を効率良く制御できる。一方で加速周波数は高速制御が可能であり、周回ビームに対する収束力を１ms程度の時間スケールで制御することが十分に可能である。 If only the acceleration frequency is controlled while the exciting current of the deflecting electromagnet or the quadrupole electromagnet is constant, the energy of the orbiting beam is changed and the position of the orbit is changed. The former affects the horizontal / vertical convergence force with respect to the circular beam, and has the same effect as the adjustment of the excitation current of the quadrupole electromagnet. Further, the latter has the same effect as the adjustment of the excitation current of the quadrupole electromagnet because the orbit is displaced from the center position of the hexapole electromagnet and affects the convergence force in the horizontal / vertical direction with respect to the orbiting beam. By combining the effects of both, the size of the stability limit (the area of the stable region) can be controlled efficiently. On the other hand, the acceleration frequency can be controlled at high speed, and the convergence force for the circulating beam can be sufficiently controlled on a time scale of about 1 ms.
本実施形態によれば、シンクロトロンの出射期間中に周回ビームを逐次加速あるいは減速する際に、制御装置６００がシンクロトロンの加速周波数を制御することで安定限界の大きさを拡大して不要な荷電粒子ビームの出射を抑制できる。これにより、ビーム輸送系で廃棄すべき荷電粒子ビームを抑制でき、荷電粒子ビームの利用効率を改善して線量率を向上し、スキャニング法での治療照射時間を短縮できる。 According to the present embodiment, when the orbiting beam is sequentially accelerated or decelerated during the synchrotron emission period, the control device 600 controls the acceleration frequency of the synchrotron, thereby increasing the size of the stability limit. The emission of the charged particle beam can be suppressed. Thereby, the charged particle beam to be discarded in the beam transport system can be suppressed, the use efficiency of the charged particle beam can be improved, the dose rate can be improved, and the treatment irradiation time by the scanning method can be shortened.
また、本実施形態によれば、高速制御が可能な加速周波数の制御で対応可能であり、インダクタンスが小さい高速動作の専用電磁石をシンクロトロンに別途設けて対処する必要が無く、システムの大型化やコスト高を回避できる。 Further, according to the present embodiment, it is possible to cope with the control of the acceleration frequency capable of high-speed control, and it is not necessary to separately provide a high-speed operation dedicated electromagnet with a small inductance in the synchrotron. High cost can be avoided.
本発明の第３の実施形態による粒子線治療システムの構成及び動作について説明する。本実施形態による粒子線治療システムの全体構成を図５に、シンクロトロンの出射期間中の詳細な運転シーケンス及び運転パラメータの時間変化を図６に示す。以下、第１及び第２の実施形態との相違点のみを説明する。 The configuration and operation of the particle beam therapy system according to the third embodiment of the present invention will be described. FIG. 5 shows the entire configuration of the particle beam therapy system according to the present embodiment, and FIG. 6 shows a detailed operation sequence and time change of operation parameters during the synchrotron emission period. Only differences from the first and second embodiments will be described below.
図６（Ｃ）（Ｅ）に示すように、本実施形態では第２の実施形態と同様に、エネルギー変更区間で加速空胴に印加する高周波電圧の周波数（加速周波数）を制御し、安定限界の大きさ（安定領域の面積）を拡大している。これにより、図６（Ｇ）の如く、エネルギー変更区間でシンクロトロンから出射される出射ビーム電流が十分に抑制できる。その場合には、ビーム輸送系のビーム遮断用電磁石で不要な出射ビームを廃棄しなくとも、図６（Ｉ）に示す理想的な照射ビーム電流が実現できる。そこで、図５ではビーム輸送系にビーム遮断電磁石と励磁用電源が配置されていない。 As shown in FIGS. 6C and 6E, in this embodiment, as in the second embodiment, the frequency (acceleration frequency) of the high-frequency voltage applied to the acceleration cavity in the energy change section is controlled, and the stability limit is reached. The size (area of the stable region) is expanded. Thereby, as shown in FIG. 6G, the outgoing beam current emitted from the synchrotron in the energy change section can be sufficiently suppressed. In that case, the ideal irradiation beam current shown in FIG. 6 (I) can be realized without discarding an unnecessary outgoing beam by the beam blocking electromagnet of the beam transport system. Therefore, in FIG. 5, the beam blocking electromagnet and the excitation power source are not arranged in the beam transport system.
本実施形態では、シンクロトロンの出射期間中に周回ビームを逐次加速あるいは減速する際に、制御装置６００がシンクロトロンの加速周波数を制御することで安定限界の大きさを拡大し不要な荷電粒子ビームの出射を十分に抑制できるので、ビーム輸送系で出射ビームを遮断する機能を敢えて設ける必要がなく、システムの簡素化・低コスト化が達成できる。 In the present embodiment, when the orbiting beam is sequentially accelerated or decelerated during the synchrotron emission period, the control device 600 controls the acceleration frequency of the synchrotron to increase the size of the stability limit, thereby eliminating an unnecessary charged particle beam. Therefore, it is not necessary to provide a function of blocking the outgoing beam in the beam transport system, and the system can be simplified and reduced in cost.
本発明は、がん治療等を目的とした粒子線治療システム以外に、シンクロトロンで加速した高エネルギーの荷電粒子ビームを、高精度に且つ所望の強度分布でターゲットに照射する必要性のある物理研究にも適用できる。 The present invention is not limited to a particle beam therapy system for cancer treatment or the like, but has a need to irradiate a target with a high-energy charged particle beam accelerated by a synchrotron with a desired intensity distribution with high accuracy. It can also be applied to research.
１１…前段加速器
２１…偏向電磁石（シンクロトロン）
２２…収束／発散型四極電磁石（シンクロトロン）
２３…六極電磁石
２４…入射装置
２５…加速空胴
２６…出射装置
２７…出射偏向装置
３１…偏向電磁石（ビーム輸送系）
３２…収束／発散型四極電磁石（ビーム輸送系）
３３…ビーム遮断用電磁石
３４…ビームダンプ
４１…患者
４２…患部
５１…走査電磁石
５２…ビームモニタ
１００…粒子線治療システム
２００…シンクロトロン
３００…ビーム輸送系
４００…治療室
５００…照射装置
６００…制御装置
２１Ａ，２２Ａ，２３Ａ，２５Ａ，２６Ａ，３３Ａ … 励磁用電源／励振用高周波電源
11: Pre-accelerator 21: Bending electromagnet (synchrotron)
22 ... Convergent / divergent quadrupole magnet (synchrotron)
23 ... Hexapole electromagnet 24 ... Injecting device 25 ... Acceleration cavity 26 ... Ejecting device 27 ... Ejecting deflection device 31 ... Deflection electromagnet (beam transport system)
32 ... Convergent / divergent quadrupole magnet (beam transport system)
33 ... Electromagnetic magnet 34 for beam blocking ... Beam dump 41 ... Patient 42 ... affected part 51 ... Scanning magnet 52 ... Beam monitor 100 ... Particle beam therapy system 200 ... Synchrotron 300 ... Beam transport system 400 ... Treatment room 500 ... Irradiation device 600 ... Control Devices 21A, 22A, 23A, 25A, 26A, 33A ... Excitation power source / Excitation high frequency power source
Claims (4)
前記シンクロトロンから出射された荷電粒子ビームを治療室まで導くビーム輸送系と、
前記治療室で患者の患部形状に合わせて荷電粒子ビームを照射する照射装置を備える粒子線治療システムにおいて、
前記シンクロトロンの出射期間中に荷電粒子ビームを逐次加速あるいは減速して複数エネルギーの荷電粒子ビームを出射し、加速あるいは減速中に前記シンクロトロンから出射される不要な荷電粒子ビームを前記ビーム輸送系で遮断する機能を有した粒子線治療システム。
After accelerating the charged particle beam incident from the front stage accelerator to a predetermined energy, the synchrotron emits the charged particle beam by exceeding the stability limit with the high frequency voltage applied to the extraction device,
A beam transport system for guiding a charged particle beam emitted from the synchrotron to a treatment room;
In a particle beam therapy system comprising an irradiation device for irradiating a charged particle beam in accordance with the shape of an affected part of a patient in the treatment room,
A charged particle beam is sequentially accelerated or decelerated during the emission period of the synchrotron to emit a multi-energy charged particle beam, and an unnecessary charged particle beam emitted from the synchrotron during acceleration or deceleration is emitted from the beam transport system. Particle beam therapy system that has the function of blocking in
During the emission period of the synchrotron that emits a charged particle beam of multiple energies by sequentially accelerating or decelerating the charged particle beam, the magnitude of the stability limit is made substantially constant by controlling the electromagnet constituting the synchrotron. 2. The particle beam therapy system according to claim 1, wherein the high frequency voltage applied to the extraction device is turned off at the time of acceleration or deceleration while maintaining.
When sequentially accelerating or decelerating the charged particle beam during the synchrotron emission period, the stability limit is enlarged by controlling the acceleration frequency of the synchrotron, and unnecessary charged particle beam emission is suppressed. The particle beam therapy system according to claim 1, wherein the system is a particle beam therapy system.
前記シンクロトロンから出射された荷電粒子ビームを治療室まで導くビーム輸送系と、
前記治療室で患者の患部形状に合わせて荷電粒子ビームを照射する照射装置を備える粒子線治療システムにおいて、
前記シンクロトロンの出射期間中に荷電粒子ビームを逐次加速あるいは減速して複数エネルギーの荷電粒子ビームを出射し、加速あるいは減速中に前記シンクロトロンの加速周波数の制御で前記安定限界の大きさを拡大し不要な荷電粒子ビームの出射を抑制する機能を有した粒子線治療システム。 After accelerating the charged particle beam incident from the front stage accelerator to a predetermined energy, the synchrotron emits the charged particle beam by exceeding the stability limit with the high frequency voltage applied to the extraction device,
A beam transport system for guiding a charged particle beam emitted from the synchrotron to a treatment room;
In a particle beam therapy system comprising an irradiation device for irradiating a charged particle beam in accordance with the shape of an affected part of a patient in the treatment room,
During the synchrotron emission period, the charged particle beam is sequentially accelerated or decelerated to emit a multi-energy charged particle beam, and the acceleration limit is increased by controlling the synchrotron acceleration frequency during the acceleration or deceleration. A particle beam therapy system having a function of suppressing the emission of unnecessary charged particle beams.
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| JP2018189465A (en) * | 2017-05-01 | 2018-11-29 | 東芝エネルギーシステムズ株式会社 | Accelerator controller, method for controlling accelerator, and particle beam radiation therapy device |
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| JP6200368B2 (en) * | 2014-04-07 | 2017-09-20 | 株式会社日立製作所 | Charged particle irradiation system and control method of charged particle beam irradiation system |
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